Morphologically Adaptive Crash Landing on a Wall: Soft‐Bodied Models of Gliding Geckos with Varying Material Stiffnesses

Abstract

Landing on vertical surfaces in challenging environments is a critical ability for multimodal robots—it allows the robot to hold position above the ground without expending energy to hover. Asian flat‐tailed geckos (Hemidactylus platyurus) are observed to glide and perch on vertical surfaces by relying on their tail and body morphology, potentially reducing the control effort to perch. This novel perching mechanism using a bioinspired physical model is discussed and its tail and body parameters to determine their influence on perching success and the kinematics of the gecko's dynamic landing maneuver are adjusted. Perching performance is evaluated by changing the model's torso and tail stiffness. Combining a compliant torso and stiff tail enables the model to passively perch on a vertical substrate with a success rate >90%, compared with ≈10% without a tail attached. A compliant torso is necessary to absorb the in‐flight kinetic energy and accommodate the uncertainties in approach conditions. Similar to the gecko's perching strategy, the stiff tail pushes against the substrate, preventing the model from falling backward head over heels. These findings highlight the critical role of tail and material stiffness for perching and provide a simplified mechanism to impart perching capabilities in robots.

Bioinspired robots can foster nature conservation

“…Unlike UAVs, perching and grasping will reduce the reliance on lift generation and thus energy expended. It will also enable the robot to hold position with minimal control effort which is often required for data collection ( Roderick et al, 2021 ; Siddall et al, 2021 ; Chellapurath et al, 2022 ). Glide capabilities, like in animals ( Zhao et al, 2019 ; Khandelwal and Hedrick, 2022 ), can increase the flight time by reducing the dependence on powered flight, reduce noise pollution and make them more robust to aerial perturbations.…”

A Year at the Forefront of Gliding Locomotion

“…(E) Soft physical models enable the investigation of the effects of morphology and the underlying movement control on gliding locomotion. Chellapurath and colleagues ( 2022 ) used a soft physical model to show the importance of torso and tail stiffness in gliding geckos to successfully perch on vertical substrates in the absence of enlarged aerodynamic surfaces (adapted from Chellapurath et al, 2022 ). 3D rendering of the soft physical model of the gecko by Dr Mrudul Chellapurath.…”

“…These platforms act as powerful tools to interact with real-world surroundings and in doing so, serve as a test bed to explore parameters, inform models, and test various hypotheses (an approach also known as ‘robophysics’; Aguilar et al, 2016 ). Chellapurath and colleagues used a simple and inexpensive soft physical model to replicate the perching behavior of gliding geckos, which is extremely challenging to elicit in live specimens ( Chellapurath et al, 2022 ; Fig. 2 E).…”